Work on resetting in baroreceptors is in progress. We have demonstrated that the resetting is unrelated to steady-state changes in the compliance of hypertensive vessel walls and that it is probably unrelated to alterations in the intrinsic properties of the baroreceptors themselves. Attention is directed, therefore, to coupling mechanisms and to destruction of low threshold baroreceptors. Work in the next year will concentrate on these two areas, largely using techniques of correlation spectroscopy and ultrastructural investigation. Work on the role of the nervous system in arrhythmias associated with coronary occlusion has demonstrated that the sympathetics and, in particular, the left stellate ganglion are crucially involved. Work on the nature of the afferent, inflow pathways from the heart which direct this output will be attempted in the next Year. BIBLIOGRAPHIC REFERENCES: Tuley, F. H., A. M. Brown and W. R. Saum. 1976. Frequency response characteristics of normotensive and hypertensive aortic baroreceptors. Biophysical J. 16: 149a. Schwartz, P. J., N. G. Snebold, and A. M. Brown. 1976. Effects of unilateral cardiac sympathetic denervation on the ventricular fibrillation threshold. Am. J. of Cardiology 37: 1034-40.